In a laser processing system, a laser processing head forms the end of a beam guidance from the laser to the processing location and focuses the laser beam onto the processing location. Laser processing heads contain supplies for working and/or inert gases, and sensors for distance control from the workpiece. The gases are discharged through a nozzle in the laser processing head towards the processing location on the workpiece. Often a laser cutting gas pressure of up to 20 bar is required for laser cutting to discharge the slag from the kerf.
For a laser power of up to approximately 5 kW, a pressure chamber exists in the cutting head through which the laser beam passes and which is sealed by a focusing lens. The cutting of different sheet thicknesses and materials requires different nozzle cross-sections and bores in the nozzle, as disclosed, for example, in German patent No. DE 3037981.
As an alternative to cutting heads with lens optics, cutting heads with mirror optics also have been used. To generate pressure, so-called annular gap nozzles are thereby generally used, which have a separate pressure chamber and which are disclosed, for example in European Patent Applications Nos. EP 0741627 A1 and EP 0989921 A1.
Mirror optics are used almost exclusively for laser welding due to the greater power and smaller gas pressures that are used with mirror optics. Moreover, mirror optics are less sensitive to soiling than lens optics, because laser welding tends to produce more soiling than laser cutting, and because mirror optics can be cooled directly.
Generally when the laser power is low, the gas is supplied concentrically to the processing location, and when the laser power is higher, it is supplied from the side.
Laser processing heads often must be slim due to the three-dimensional tasks they perform and to minimize the disturbing (abutting) contour of the head.
To render the machines more flexible, a universally usable processing head is desired that requires as little manual adjustment as possible, i.e., the following adjustments are eliminated: changing of the processing head when switching between laser cutting and laser welding; changing the nozzle to adjust for different materials and material thicknesses; and adjustment of the separation between workpiece and processing head to the respective processing task. These changes are conventionally realized in most cases through mechanical adjustment, pivoting and tilting mechanisms, through beam setting points or through changing stations, where the processing head or the nozzle are replaced as describe, for example, in European Patent No. EP 0411535.